I think I remember oohing and ahhing over pics when you got that big handsome lug.
I’m so sorry about your little one.
When we got the mastiff as a 7 wks pup, he weighed 30 pounds, and the minpin weighed about 7 pounds. She looked him over, licked him quite a bit in a motherly way, and then urged him to follow her outside to the corner of the yard where she did her business. He learned immediately (mastiffs are very bright) and only ever had one accident.
He followed this one around for weeks. She did not chew furniture, so he did not chew furniture. She’d bark and sit for a treat, and he learned that from her. She’d pile her toys up and snarl if he got into them, so he learned to keep his toys in a basket. He watched her get her collar and leash put on, and submitted to the same thing, with a lot of play.
She’s been the “teacher dog,” and took her responsibility seriously. We had her spayed as a puppy, but she never lost her mother instinct. The mastiff took to “drying” her off with his tongue, when they came in from the rain or snow. I think he’ll miss her as much as I will. I’ll put one of her pillows in his toy basket. I did that with one of my husband’s shoes when he died, so the mastiff would have something to carry around — he used to carry it to his bed, and lay his head on it, now it is at the bottom of the toy basket, “flavoring” them all with fading scent.